Passion Pit have cancelled six concerts, citing frontman Michael Angelakos's fragile mental state. The American indie band have cleared their schedule until 2 August, apologising to fans and thanking them "for understanding".

"In order for me to ensure that there will be no further disruptions," Angelakos wrote in a special message, "I am going to take [this] time to work on improving my mental health … I hope to see all of you very soon in a much different light." Having cancelled gigs in Nashville, Knoxville, Charlotte, Dover, Norfolk and New York, the band will resume their tour in Chicago next month.

Passion Pit are due to release their second album, Gossamer, on 23 July. Angelakos suffers from "so much stress", he said in a recent interview with the Observer. "I'm always in crisis." The singer suffers from bipolar disorder and has previously struggled with alcohol abuse and chronic fatigue.

"I went to a vocal research centre, which is where Adele, everyone, goes, and they said you've got to chill out," he said. "I do the records, I write the songs, I bring the songs to the band, the band learns them, I come back in, I tweak everything, we make sure everything works perfectly, and then we go onstage … I mean the amount of pressure I'm under right now is just immense."

Passion Pit are due to appear at this year's Reading and Leeds festivals, at the end of August, as part of their world tour.